Bordering the cold, gray North Sea, the upper reaches of the Netherlands are dominated by flat, sandy farmland stretching as far as the eye can see. This quiet, windswept landscape, some of which sits below sea level, is an unlikely contender to become a major chemical industry hub. But momentum is building among Dutch research organizations to turn it into a center for the sustainable production of biofuels and specialty chemicals from a largely untapped resource: seaweed.
“The idea is to transform the North Sea into an energy- and raw-material-generating region,” says Jaap van Hal, innovation manager for biorefining at TNO, a Dutch government-funded research institute with expertise in converting biomass into fuels and chemicals.
The proposal to mass-produce and process seaweed in the region has attracted funding from the European Union and national and regional Dutch governments. The endeavor requires companies to cultivate and harvest seaweed, as well as have the know-how to turn the macroalgae into products. Fortunately, organizations with this expertise are already in place in the region.
It’s far from clear, though, whether the Dutch will be able to transform what is largely a state-funded endeavor into an economically viable business. The central challenge will be to reduce the cost of large-scale seaweed cultivation, harvesting, and upgrading to a fraction of current levels.
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We can get back up to 75% of nutrients entering the oceans with seaweed as a filter. Reinier Nauta, marine biologist, NIOZ and Saline Farming
For sugar kelp, a seaweed rich in sugars that is ideal for converting into fuels and chemicals, this means devising materials on which the macroalgae can grow in the North Sea. In a bid to make harvesting easier, marine biologists in the Netherlands are also trying out cultivation systems for fast-growing seaweed such as Ulva lactuca—also known as sea lettuce—in saltwater tanks on land. Meanwhile, other organizations, including Wageningen University & Research (WUR), are working on extracting compounds from seaweed to make products such as animal-feed additives.
The Dutch government’s goal is to grow and process seaweed on a huge scale. Officials say a seaweed industry could take advantage of infrastructure being put in place to support the country’s 2050 sustainable energy plan, which involves setting aside one-quarter of the country’s territorial waters in the North Sea for wind turbines.
To that end, technology development and testing are already well underway. Researchers from various government-funded institutes are testing seaweed cultivation methods in the North Sea in locations off the Dutch and Belgian coasts. Tests in a seaweed farm west of Amsterdam show that seaweed can be grown year-round with a yield of 25 metric tons of dried product per hectare per year.
The chemistry component of the Dutch seaweed initiative took a major step forward at the end of 2018 when TNO opened a lab in Petten, just north of Amsterdam, dedicated to processing and testing seaweed. Nestled in the sand dunes bordering the North Sea, the lab is intended to act as a catalyst for seaweed production and processing in the Netherlands and beyond.
TNO is providing lab services to all interested parties. Scientists at the lab can produce seaweed extract, clean it up, and undertake chemical synthesis to make a target compound and, if the partner desires, undertake a conceptual design of an integrated process, Van Hal says.
For example, TNO is working with WUR, which is developing biotech methods for processing seaweed into useful compounds and with ocean institute Marin and water management institute Deltares, which have already built a demonstration-scale wind turbine park that integrates seaweed production. “We have a concerted effort with all these research institutes,” Van Hal says.
TNO has a team of about 60 people pursuing all things biomass, including about 12 full-time staff working in the seaweed lab on a range of macroalgae species.
Although it opened only months ago, the lab is already receiving inquiries from around the world, Van Hal says. “Interest is building.” Companies such as the Dutch seaweed cultivation specialist Hortimare are working with TNO’s scientists to help identify which seaweed species are best suited to biofuel production.
TNO is willing to license its intellectual property and know-how on making sugars for producing biobutanol, a replacement for diesel. The organization also has technology relating to the production of sugars for novel furanic-based biofuels.
“It’s a long way to go,” Van Hal says. “As with many sustainable development projects, we are at the beginning of a steep learning curve.” TNO has capacity to produce biofuel in batches of 100 L.
The Dutch are also involved in efforts to scale up seaweed production outside the Netherlands. In 2016, the EU launched MacroFuels, a 4-year, $6 million project to dramatically reduce the cost of growing seaweed while also making more seaweed available for biofuel tests.
The 11 organizations participating in MacroFuels, including TNO and the Dutch catalysis firm Avantium, are testing biofuel production processes on brown, red, and green seaweeds, including sugar kelp. Their projects include the development of both bio- and thermochemical routes to bioethanol, biobutanol, and other fuels.
The MacroFuels partners are also advancing low-cost methods for cultivating seaweed, such as by rotating crops on various growing substrates anchored in the sea. The partners are due to complete their projects at the end of this year.
Another EU-funded project, Macro Cascade, seeks to use compounds present in seaweed to make specialty chemicals. It features 13 organizations, including WUR, TNO, and Hortimare.
Launched in November 2016 with almost $5 million (€ 4.2 million) in EU funding, Macro Cascade aims to evaluate seaweed biorefining on laboratory, pilot, and commercial scales.
Similar to partners of MacroFuels, the Macro Cascade partners are developing novel substrates on which to grow seaweed in the open ocean. The goal is to combine open-ocean growth techniques with new mechanical-harvesting technologies to increase biomass yield by a factor of five and reduce overall cultivation costs by up to 75%.
Macro Cascade has been quiet about its progress, though members hinted on Twitter earlier this year that the molecules they could extract from seaweed include β-glucans, a group of polysaccharides that have been shown in studies to enhance the immune response of animals (Anim. Feed Sci. Technol. 2019, DOI: 10.1016/j.anifeedsci.2018.12.004).
Beyond Macro Cascade, individual scientists are also investigating seaweed cultivation. With an eye on global population growth and increasing constraints on arable land, WUR researcher Alejandro Parodi has been investigating whether seaweed could be a good replacement for animal-sourced foods.
His conclusion is that sugar kelp will need to become a major component of the human diet alongside other “future foods” such as black soldier fly larvae, mealworm larvae, Chlorella microalgae, and cultured meat. He published the findings of his study in December 2018 in the journal Nature Sustainability (DOI: 10.1038/s41893-018-0189-7).
Setting aside just 2% of Earth’s sea surface for seaweed cultivation would ensure enough food for the whole world, according to WUR. Compared with raising animals, sugar kelp production has a far lower impact on greenhouse gas emissions per unit of protein and avoids issues associated with land use. Making sugar kelp attractive and affordable at large scale will require private and public intervention, however, Parodi warns in his study.
A number of other organizations, including NIOZ (the Royal Netherlands Institute for Sea Research), are striving to identify optimal cultivation systems for growing seaweed for food and other applications. NIOZ’s research center on the island of Texel is an hour’s drive and a brief ferry ride away from TNO’s seaweed lab in Petten. It houses 250 scientists studying various aspects of the marine environment. One of them is marine biologist Reinier Nauta. A quarter of Nauta’s time is dedicated to NIOZ, and the rest to Saline Farming, a start-up company that advises on growing crops in salt water.
Nauta’s research at NIOZ relates mainly to the cultivation of Ulva and sugar kelp. He aims to determine the optimal growing conditions for the seaweed using ten 1,500 L tanks and three 25,000 L tanks at the NIOZ Seaweed Research Centre.
Ulva is particularly interesting as a land-based crop grown in tanks. It is high in nutrients and thus suitable for food and feed applications. And it can be grown in brackish water as well as seawater. “We can lower the water salinity by half, and Ulva still grows well,” Nauta says.
But growing seaweed in tanks on land is complex. “pH levels in a tank change the day after a harvest,” Nauta says. “And, among other problems, too many nutrients cause bacterial growth.”
Get the environmental conditions right, though, and Ulva, a tissue-like seaweed with no root anchor, will grow at a rate of about 10% by mass per day, Nauta says.
In contrast to Ulva, sugar kelp has a strong anchor system and is better suited to open-sea cultivation on a substrate such as a large fibrous mat, he says. It can grow up to 2 m in the main growing season, from November to May.
The cultivation of seaweed is at an early stage, Nauta acknowledges. Four to 5 years of growth trials are still to come for sugar kelp, and more for Ulva.
Ultimately, though, industrial seaweed can be good for the oceans, he says. It can remove nutrients such as phosphorus and nitrogen from fertilizers washed from fields, preventing them from causing microalgae blooms.
“We can get back up to 75% of nutrients entering the oceans with seaweed as a filter. It is a circular loop,” Nauta says.
While seaweed cultivation trials are still in early stages, the Dutch are already starting to get a taste for seaweed, says Mark Kulsdom, cofounder of the Dutch Weed Burger, a company that infuses veggie burgers with seaweed like sugar kelp and Ulva. The firm’s products include a beer-battered seaweed burger with an eggplant topping.
“Seaweed is going to be the next-level new protein source,” Kulsdom says. “It is future-proof. It respects the ocean. We are ready to scale up and are really going for it in the coming year.”
Large-scale seaweed supply and processing in the Netherlands is still years off, though, and the Dutch projects have yet to attract major investments from biofuel and chemical companies. Furthermore, the business case for companies in the value chain is far from certain. Tellingly, Nauta’s main employer, Saline Farming, recently disclosed that it has filed for bankruptcy.
Even the ambitious Dutch appear to have some choppy waters to cross before they can bring their seaweed industry vision ashore.
Published on cen.acs.org